In building construction and maintenance, a large ground based crane is commonly used to lift materials to the sides and top of a building. Such ground based cranes are very expensive to rent and operate, commonly requiring a large number of personnel to transport, set up, maneuver, and operate the crane. Additionally, such ground based cranes have a limited reach, thereby restricting the operational capability of the crane, and are too large and heavy to enter and work within the interior portions of a building.
Many tall buildings are relatively wide at the lower floors, and include a narrower central tower structure comprising a large number of floors. This type of building configuration prevents a ground based crane from extending upwards and inwards a sufficient distance to reach the floors contained in the central tower structure of the building. Also, the large building can be surrounded by many adjacent buildings, preventing ground crane access for building construction, renovation, and maintenance. Thus, a ground based crane generally cannot be used during the construction and maintenance of the central tower structure.
To overcome the height limitation of ground based cranes during the construction of a building, a mast or derrick type roof based crane is commonly used. The roof based crane is typically mounted to the uppermost portion of the building under construction, such that the effective operating height of the crane relative to the ground increases as the height of the building increases. The roof based crane generally includes a boom that can only access the exterior of the building, and that is not capable of reaching into the floors of the building. After construction has been completed, the roof based crane is typically dismantled, and is not available for subsequent maintenance of the exterior of the building.
Thus, there is clearly a need for a crane that can be used in all phases of building construction and maintenance, both on the exterior and interior portions of a building, that does not suffer from the height, weight, and operational constraints of currently available ground and roof based cranes, and that can be easily setup and maneuvered throughout all areas of a building with a minimal amount of effort.